"I cannot give any scientist of any age better advice than this: the intensity of a conviction that a hypothesis is true has no bearing over whether it is true or not"
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Medawar’s line is a cool splash of antifreeze on science’s most seductive engine: the thrill of being right. He’s not just warning against “bias” in the bland, classroom sense. He’s naming a structural hazard of the scientific temperament itself, where intelligence and passion can fuse into a private religion. The more elegant your hypothesis, the more it flatters your identity as a discoverer, the easier it becomes to mistake emotional voltage for evidentiary charge.
The intent is almost parental: a senior scientist talking to younger ones about how self-deception scales with ambition. “Intensity” is doing a lot of work here. It captures the lab’s quiet drama - late nights, reputations on the line, the intoxicating coherence of a theory that suddenly makes the world feel legible. Medawar’s subtext is that conviction is not merely irrelevant to truth; it can actively interfere with the machinery that gets you there. If you need your idea to be true, you will start negotiating with the data: overfitting, cherry-picking, inventing ad hoc fixes that preserve the story and postpone embarrassment.
Context matters: Medawar helped shape modern thinking about scientific method and its psychological pitfalls, pushing back on the romantic myth that science advances by pure, heroic induction. This sentence aligns with Popper-era humility but keeps its edge: nature doesn’t bargain. Reality is not impressed by sincerity, only by tests that can break your favorite thought.
The intent is almost parental: a senior scientist talking to younger ones about how self-deception scales with ambition. “Intensity” is doing a lot of work here. It captures the lab’s quiet drama - late nights, reputations on the line, the intoxicating coherence of a theory that suddenly makes the world feel legible. Medawar’s subtext is that conviction is not merely irrelevant to truth; it can actively interfere with the machinery that gets you there. If you need your idea to be true, you will start negotiating with the data: overfitting, cherry-picking, inventing ad hoc fixes that preserve the story and postpone embarrassment.
Context matters: Medawar helped shape modern thinking about scientific method and its psychological pitfalls, pushing back on the romantic myth that science advances by pure, heroic induction. This sentence aligns with Popper-era humility but keeps its edge: nature doesn’t bargain. Reality is not impressed by sincerity, only by tests that can break your favorite thought.
Quote Details
| Topic | Reason & Logic |
|---|---|
| Source | Peter Medawar — attributed in his entry on Wikiquote; phrasing matches the line commonly cited from his essay collection 'Advice to a Young Scientist'. |
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